It is well known that mulch technology can effectively improve crop yield, but residual mulch will also damage soil structure and cause agricultural pollution. At present, China has developed a variety of residual film recycling machine to solve this problem. Aiming at the problem of impurities congestion in the process of picking up plastic film with the following film recycling machine, a new film picking up mechanism was designed based on the existing types of film recycling machine. The main structural parameters of the height of the working rod of wheel to remove impurities and the spacing of wheel to remove impurities were determined by analyzing the separation process of membrane soil in the mechanism，and through the analysis of the process of picking up the mulch film, the travel speed of the machine and the rotation speed of wheel to remove impurities were determined. The rotating speed of the wheel to remove impurities, the moving speed of the machine and the spacing of the wheel to remove impurities were determined as the main factors of the test. The ratio of membrane to soil separation and the ratio of impurities removal were taken as the response values. Design-Expert 8.0.5 was used for regression analysis and response surface analysis, and the influence of various factors on the membrane soil separation ratio and the impurity removal ratio was determined by using this method. The results showed that the degree of influence on the separation ratio of mulched soil and the ratio of impurities discharged both were the rotating speed of the wheel to remove impurities, the moving speed of the machine and the spacing of the wheel to remove impurities. Moreover, a ternary quadratic regression model was established, which contained these factors. The nonlinear optimization method was used to optimize the parameters of the mechanism, the results showed that when the rotating speed of the wheel to remove impurities was 26.2r/min, the moving speed of the machine was 1.23m/s and the spacing of the wheel to remove impurities was 139.95mm that the maximum theoretical value of membrane soil separation ratio was 91.49%, and the maximum theoretical value of impurity removal ratio was 92.92%.